1. Field of the Invention
The subject invention generally pertains to a vehicle restraint and more specifically to one that moves to a low-profile stored position.
2. Description of Related Art
When a truck backs up against a dock for loading or unloading the truck, a generally safe practice is to restrain the truck to prevent it from accidentally pulling away from the dock. This is often accomplished by a hook-style vehicle restraint that engages what is known as an ICC bar or a Rear Impact Guard (RIG). An ICC bar or RIG is basically a bumper in the form of a horizontal bar or beam that runs along the rear of a truck, below the truck bed. Its primary purpose is to prevent an automobile from under-riding the truck in a rear-end collision. A conventional hook-style restraint includes a hook that moves between a lowered stored position and a raised operative position. The lowered stored position allows the ICC bar to pass over the hook as the truck backs up against the dock. The hook then rises to its operative position where the hook engages the bar to restrain the vehicle.
With many hook-style vehicle restraints, a hook""s stored position can create several problems. First, a stored hook protruding out from the face of the dock can be an obstacle that prevents smaller vehicles or those with low ground clearance from getting close enough to the dock for effective loading and unloading. For example, when a protruding hook forces a pick-up truck or van to park a short distance away from the dock, the protruding hook can be a tripping hazard for anyone on the driveway trying to load or unload the vehicle. Second, in some cases, a truck or trailer""s ICC bar is too low to clear the top of a stored hook. This problem is becoming more prevalent, as newer vehicles are being built with lower beds. And third, a stored hook protruding from the face of a dock can obstruct snow removal equipment.
To address some of these problems, U.S. Pat. No. 4,664,582 discloses a truck restraint with a hook that not only moves vertically between a raised operative position and a lowered stored position, but also rotates about a vertical axis. The rotation allows the hook to alternately swing between being perpendicular to the dock face or generally flat up against it. The ""582 restraint, however, has a stored height that may still interfere with some vehicles with a relatively low ICC bar. Although the hook, in its stored position, might be below the bar initially, the hook has to raise some in order for the hook to rotate outward away from the dock face. The initial ascent of the hook to effect the rotation may place the hook above the bar before the hook is able to swing underneath it. The initial lift can be minimized by reducing the steepness of the inclined edge that causes the hook to rotate, but that increases the upward force required to lift the hook. And increasing the upward force can lead to a situation that can damage the ICC bar. For example, once the hook rotates outward and off the inclined edge, the sustained high upward force is free to simply accelerate the hook upward at an speed until the hook strikes the ICC bar. A sufficiently high impact could damage the bar. Moreover, a sufficiently high upward force on the hook may limit the vehicle from normal vertical float. Vertical float of a couple of inches or more is common and is caused by varying cargo weight and the weight of a forklift driving onto the bed of the vehicle as it is being loaded or unloaded. If the hook provides no give to slightly descend as the truck is loaded, the added weight could crush the ICC bar between the bed of the vehicle and the hook, as ICC bars are not normally intended to support the weight of the truck""s cargo.
Some vehicle restraints have a rotational hook, as disclosed in U.S. Pat. Nos. 4,553,895; 4,605,353; and Re33,154. With these restraints, however, the hook is rotated manually. Also, the hooks of the patented restraints are lowered onto an ICC bar, which means the vehicle must have clearance above its ICC bar in order for the hook to swing into position. Not all vehicles provide such clearance.
Another vehicle restraint, disclosed in U.S. Pat. No. 4,634,334, includes a hook that is power-rotated between a stored position and an operative position. However, except for hook""s rotation, the restraint does not move vertically to accommodate ICC bars of various heights.
In order to provide a low-impact vehicle restraint with a low-profile stored position, a restraint is provided with a hook that moves both vertically and rotationally between a lowered stored position and a raised operative position. In the raised operative position the hook is adapted to engage an ICC bar of a vehicle to limit the vehicle""s movement away from a loading dock. In the lowered stored position, the hook""s position allows the vehicle to back up against the dock. The hook""s rotation is such that it has a minimal affect on the restraint""s effective range, wherein the range is defined by those elevations at which an ICC bar can be effectively restrained by the hook. The restraint includes a resilient member that provides upward movement of the hook while allowing some downward movement of the vehicle being restrained.
In some embodiments, the hook rotates about an axis that is generally perpendicular to the dock face so that the hook in its lowered stored position lies rather low to the ground to accommodate especially low ICC bars or vehicles with relatively low ground clearance.
In some embodiments, the rotation of the hook is completed before the hook begins rising, thus being able to accommodate relatively low ICC bars.
In some embodiments, the force that rotates the hook is applied at a generally uniform distance from the hook""s rotational axis to avoid a peak force or peak torque that might slam the hook into position.
In some embodiments, the force that rotates the hook is applied at a generally uniform distance from the hook""s rotational axis so that when the force is brought on by vertical movement of the hook, peak vertical forces that may tend to slam the hook up against the underside of the ICC bar are avoided.
In some embodiments, the force that rotates the hook is applied in a direction generally perpendicular to the hook""s rotational axis to keep the total force less than what would otherwise be required if the force were just a component of a greater force applied at an angle other than ninety degrees to the rotational axis.
In some embodiments, a resilient member, such as a spring, provides upward movement of the hook to engage an ICC bar of a vehicle while allowing some downward movement of the vehicle once it is restrained.
In some embodiments, a resilient member, such as a spring, avoids damaging an ICC bar of a vehicle by limiting the upward thrust that a restraining member can exert against the bar.